We've had regular threads about limited and standard MtG for a while now. So I thought I'd share my thoughts about the format I most often play Modern. For the uninitiated Modern is the newest of the eternal formats allowing cards from 8th edition forward. Thus about 65% of the cards that have been printed are playable in Modern that percentage rises each time wizards prints a new expansion.

Why play Modern anyway?
The appeal of any eternal format is you get to play more powerful cards and keep playing with them forever, or at least longer than the ~2 years that cards are in standard. Of the eternal formats Modern is the one WotC is most committed to support with format staples reprinted in the biennial Modern Masters sets. You can a acquire a tournament level modern deck for under 200 tickets on Magic online (and you should play Modern online because it's three times as expensive in paper and much harder to find games)

Modern is also the most accessible format in which combo decks are played and if MtG Top8 is any indication it's the format where combo is the highest percentage of the metagame. It also has some of the weirder and more inventive combo deck I've seen played. People will do things like try to take infinite turns, cascade into living end, or use Angel's Grace and add Nausaem to draw your deck. That said let's check out the combo decks that are currently popular.

Valakut
The problem with ramp decks is since that you play a bunch of sketchy cards in order to cast bigger threats you often draw too many threats and not enough extra mana or vise versa. Valakut helps this by making your ramp also a threat. The combination of scapeshift and Valakut adds the explosiveness that modern requires. There are two versions of this deck commonly played. One straight R/G with Primeval Titan the other in Temur Colors with counterspells.

Valakut is slower than many combo decks with turn 3 wins impossible for most lists and turn 4 mostly being magical christmas land scenarios. The upside is that the R/G versions are very hard to distrupt and the blue version is a reasonable control deck in it's own right. Some versions get cute with Through the Breach.

The Deck Formerly Known as Pod
Currently know as Creatures Toolbox this deck is part of a long line of creature based combo decks playing Chord. Vizier of Remedies and Devoted Druid is infinite mana, Vizier, Kitchen Finks and a sac outlet is infinite life. Chord, CoCo and occasionally Eldritch Evolution help set up those combos.

Should the combo aspect of the deck fail you have the extremely reasonable plan of winning via playing creatures and attacking with them. Most current versions play Eternal Witness for the potential to recur Colected Company.

While turn 3 wins are possible Creatures Toolbox is built more for resiliency than speed turn 4 wins are more likely.
Storm
Storm is one of the oldest decks in Modern and it has endured despite having more cards banned from it than any deck in the formats history. Even when it wasn't good people still played it because there is still beauty in the world that's worth defending. With the printing of Baral Storm is tier 1 once more.

The goal of Storm is cast 19 spells and then play Grapeshot (or 9 spells and cast two Grapeshots). Since Seathing Song was banned Storm has needed to rely on some type of permanent enabler to get to 19. The current version uses Baral and Goblin Electromancer in order to make your spells cheap turning Pyretic and Desperate Rituals into Dark rituals and letting Manamophose net a mana. Past in Flames let's you recast all your spells which alongside the heavy order of cantrips you play with let's go through a big chunk of your deck.

Gifts Ungiven is the glue that holds the deck together as the Flashback on Past in Flames means that their choice of what to give you is rarely relevant. While the deck is softer to creature removal than previous versions the high density filtering cantrips and ability to cast out of the graveyard makes Strom surprisingly resilient.

Storm is usually a turn 4 deck unless of course you land a Baral turn 2 and they don't do anything about it. In that case going off turn 3 is a realistic possibility.

Ad Nauseam
Ad Nauseam does't kill you if you cast Angel's Grace (of Phyrexian Unlife) first even if you draw your deck. So you get to draw you deck and then kill them with Lightning Storm. Everything else is extra mana so you can pop off earlier along with maindeck Pact of Negation if they try to do something about it.

Ad Nauseam can win at instant speed and with no on board permanents (beyond mana sources) and as early as turn 3 though it's rare to see it happen. The problem with Ad Nauseam is that it's a two card combo and you only have extra copies for one of your cards. Hand distruption can set you back significantly and you play a bunch of cards that are basically blanks outside the combo.